Malignant melanoma is the most deadly of all skin cancers. A protein called B-Raf is mutated to a constitutively active form (V600E-B-Raf) in approximately 90% of moles and premalignant early melanoma cells. SiRNA can be made that specifically reduces expression of mutant V600E-B-Raf protein but not normal wild-type protein. Targeting V600E-B-Raf using this siRNA inhibits early melanoma development making it an ideal chemopreventive agent. The challenge is to develop a strategy to deliver this chemopreventive siRNA against V600E-B-Raf into cells in the skin, which is the goal of this project. Currently, no technology or approach utilizes siRNA as a chemopreventive agent to inhibit early melanoma development. The central chemoprevention hypothesis for the proposed research is that siRNA against mutant V600E-B-Raf delivered via novel ultrasound-liposome technology into skin containing early melanocytic lesions will be an effective chemopreventive agent for reversing or retarding development of moles or early lesions. We formulated this hypothesis based on preliminary findings using a model in which skin is made in a tissue culture dish that contains cells derived from early-stage melanomas, which develop into tumors histologically resembling early premalignant melanomas. As proof-of-principle, we can show that siRNA against mutant V600E-B-Raf retards development of these early melanocytic lesions. Furthermore, we are developing a novel and innovative technology for delivering siRNA into cancer cells in skin that combines skin ultrasonication together with liposomal delivery vehicles. We are prepared to undertake the proposed research, having identified mutant V600E-B-Raf as a potential chemopreventive target. Furthermore, we have preliminary data using skin reconstructs containing early melanomas, which have been ultrasonicated and exposed to liposomes loaded with siRNA showing the potential utility of this technology. In addition, we have assembled a research team that uniquely combines multidisciplinary experts in melanoma, skin reconstruction, siRNA targeting, as well as ultrasound and liposome technology, each of who has long-standing research interests in melanoma and development of chemopreventive agents. Development of this chemopreventive agent would significantly impact human health by reducing melanoma development, thereby directly decreasing mortality rates. [unreadable] [unreadable] [unreadable]